Yes one above the other. one forward facing one rear facing. hopefully with the drivers/cones aligned, they seem to be front mount based on the photos I'll see when the drivers arrive.
With some kind of rear magnet mount or constraint but also baffle mounted too like a clamp system.
Depending on the sensitivity depends on what I do with the bass... I did plan to use A&D bass drivers as and when I have sorted out the upper part and how sensitive they are. As the drivers were £7.50 each including shipping I didn't want a huge expense... there are some 12 inch drivers from Monacor for £26 each here:
http://www.bluearan.co.uk/index.php?id=MON104000&browsemode=manufacturerNot sure how they compare to the A&D drivers though
I have a pair of Ion Obelisks amplifiers (3 and a 3X/XPAC1 both have pre in and power in (in the integrated amps) which I intent to use for active duty for 100Hz>full range and below 100Hz
In addition I was reading the driver improvement thread here last night >
http://www.diyaudio.com/forums/multi-way/119676-enabl-listening-impressions-techniques-2.htmlAnd a thread about using a T transformer in the bass circuit to boost the level with a resonance, not fully understood it yet...
My background is sound and vibration engineering so should be fun
John